The present invention relates to an oxy-fuel burner of the type comprising at least one fuel supply pipe and at least one pipe for supplying an oxygen-rich gas, the said outlets of the said pipes being directed approximately in the same direction, the burner being designed to be mounted through a wall of a furnace with the pipes directed into the furnace.
Such burners are used especially in furnaces for melting enamels or for melting aluminum. They are placed through the wall of the furnace via a brick right through which passes a hole, this brick being called a quarl. The outlet ends of the fuel supply pipe and of the oxygen-rich gas supply pipe emerge in the passage of the quarl. The latter generally has a profile which diverges into the furnace. The root of the flame is located within the quarl in the zone where the fuel and the oxygen-rich gas meet and mix.
In order to allow a burner to be ignited in an enclosure in which the temperature is below the spontaneous ignition temperature of the fuel, it is necessary to use a device for igniting the burner. Such a device is therefore known to be provided in the wall of the furnace. In order for the ignition device to be close to the zone where the fuel and the oxygen-rich gas meet, the igniting device is generally placed in a duct provided in the quarl and emerging in the passage passing through the latter.
Likewise, in order to check the presence of the flame at the outlet of the burner, it is known to provide means for detecting ultraviolet radiation near the flame retention zone. These means comprise, for example, a cell for detecting ultraviolet radiation. This cell is housed in a duct made in the quarl and emerging in the passage of the latter.
Quarls are made of refractory. The presence of ducts emerging in the passage passing through the quarls weakens the structure of them. In addition, these emerging ducts cause the flow conditions of the gas stream inside the divergent passage to degrade.
The object of the invention is to solve the abovementioned problem by providing a burner equipped With auxiliary devices, such as an igniting device or a device for analysing the flame, without this impairing the mechanical strength of the quarl and the quality of the flow of the gases through the latter.
For this purpose, the subject of the invention is an oxy-fuel burner of the aforementioned type, characterized in that it carries at least one auxiliary member intended to act on the flame, and in that the said auxiliary member is placed on the burner upstream of the zone where the fuel gas and the oxygen-rich gas meet.
Depending on the particular embodiments, the burner comprises one or more of the following characteristics;
it comprises a body containing the said pipes, which body is open only towards the inside of the furnace and comprises at least one tap for connection to a supply for feeding with oxygen-rich gas, the body thus defining the said oxygen-rich gas supply pipe, the body is penetrated by the or each fuel supply pipe and the or each auxiliary member is attached to the body so that it is swept with the flow of oxygen-rich gas when feeding the burner with oxygen-rich gas;
the or each fuel supply pipe passing through the body is removably mounted on the latter;
the or each auxiliary member has a main operating axis and the or each main axis defines, with the said outlet direction of the pipes, an angle of between 0and 45xc2x0 and advantageously of between 0 and 20xc2x0;
the or each auxiliary member is oriented in order to act in the flame retention zone;
one of the auxiliary members comprises a device for igniting the flame;
the device for igniting the flame comprises a tube for supplying an igniting flame, which tube has its outlet end placed at a distance of between 2 and 10 cm upstream of the zone where the fuel meets the oxygen-rich gas;
one of the auxiliary members comprises a window;
one of the auxiliary members comprises a device for analysing the flame; and
the said device for analysing the flame comprises a cell for measuring the light intensity produced by the flame in the ultraviolet zone and the said cell is connected to means for comparing the measured intensity with at least two predetermined threshold values in order to deduce therefrom that the burner is in an incorrect operating state.